Maternal food restriction during pregnancy affects offspring development and swimming performance in a placental live-bearing fish

How pregnant mothers allocate limited resources to different biological
functions such as maintenance, somatic growth, and reproduction can have
profound implications for early life development and survival of
offspring. Here we examined the effects of maternal food restriction
during pregnancy on offspring in the matrotrophic (i.e. mother-nourishment
throughout gestation) live-bearing fish species Phalloptychus januarius
(Poeciliidae). We fed pregnant females either with a ‘low-food’ or
‘high-food’ ration for six weeks and quantified the consequences for
offspring size and body fat at birth and one week after birth. We further
measured fast-start escape performance of offspring at birth, as well as
swimming kinematics during prey capture at zero, two, and seven days after
birth. We found that the length of maternal food restriction during
pregnancy negatively affected offspring dry mass and lean dry mass at
birth, as well as body fat gain during the first week after birth.
Moreover, it impacted the locomotor performance of offspring during prey
capture at, and during the first week after, birth. We did not observe an
effect of food restriction on fast-start escape performance of offspring.
Our study suggests that matrotrophic poeciliid fish are maladapted to
unpredictably fluctuating resource environments, because sudden reductions
in maternal food availability during pregnancy result in smaller offspring
with slower postnatal body fat gain and an inhibition of postnatal
improving swimming skills during feeding, potentially leading to lower
competitive abilities after birth.